1. Field of the Invention
This invention relates to grinding apparatus. More particularly, this invention relates to a grinding apparatus that facilitates highly efficient grinding of granular and large particle products as well as tough fiber dry grain products such as barely and waste gypsum.
2. Description of the Prior Art
Present product grinding and comminuting apparatus are known in the art for reducing the size of materials such as food products, chemicals, rubbers, resins, garbage (food waste), waste-paper, wood chips, waste fiber (cloth, gypsum), plastics, glass, metal chips or the like. Conventional grinding/comminuting apparatus such as that disclosed in U.S. Pat. No. 4,129,260, issued Dec. 12, 1978 to Baker, entitled Garbage Disposal, and U.S. Pat. No. 3,973,735, issued Aug. 10, 1976 to Ito et al., entitled Apparatus For Pulverizing And Sorting Municipal Waste, typically include a grinding chamber with high speed rotating beaters/hammers that tear, shred, slash, cut and grind one or more desired products to a desired particle size as the desired product(s) are forced between the rotating beaters/hammers and a set of breaker bars and to a very limited extent, also between the rotating beaters/hammers and one or more screening elements. Conventional screening elements for grinding and comminuting apparatus such as disclosed in U.S. Pat. No. 5,526,988, issued Jun. 18, 1996 to Rine, entitled Comminuting Apparatus With Tangentially Directed Discharge, are generally well known items and are currently in wide-spread use. These screening elements may include herringbone slots, round perforations, cross slot perforation screens, and jump gap screens in combination with a drum-type structure such as disclosed in U.S. Pat. No. 4,076,177, issued Feb. 28, 1978 to Hirayama et al., entitled Pulverizing Method And Apparatus, to form a grinding/comminuting apparatus for feeding the constituents axially there through so that the resulting pulverized constituents can be discharged at different axial positions depending upon the progress of pulverization and the selected screening elements. A significant disadvantage accompanying conventional grinding/comminuting apparatus known and used in the art is reduced grinding/comminuting efficiency due to the different radial distance between the axial centerline of the rotating shaft used to rotate the beaters/hammers and the working surfaces of the screening elements as compared with the working surfaces of the beaters/hammers. For example, known grinding/comminuting apparatus of the type using breaker bars and screening elements use the breaker bars to accomplish nearly all grinding/comminuting action of constituents that ultimately pass through the aforesaid screening elements. Constituents that do not immediately pass through the screening elements continue to be pulverized between the beaters/hammers and the breaker bars until sufficiently reduced to a size that is sufficiently small to allow the filtering process to continue to completion. It is readily apparent from the above, that the grinding/comminuting action that occurs in a drum type apparatus is one of the important factors in providing a highly efficient pulverizing process.